Use of various electronic devices has increased substantially in recent years. For example, use of laptops, mobile telephones, Blackberrys, pagers, IPods, etc. have become common in public places such as coffee shops, restaurants, college campuses, businesses, etc.
Users demand their electronic devices to be integrated such that one electronic device provides various functionalities. For example, most mobile devices (e.g., iPhone, Blackberry, Treo, etc.) can now be operated as a computer, a music player, a game console, a telephone, etc. This extends the typical use duration and increases the power demand of the device between recharge cycles. Unfortunately, increase in the device functionality increases the power demand, thereby increasing the frequency by which the device needs to be recharged by the user.
Batteries are used to provide mobility to electronic devices. Unfortunately functionalities places a drain on battery power. Accordingly, in order to save batter power and increase battery life, devices selectively turn on/off various intra sub-units in response to user demand. Various power management methods have been developed in order to selectively turn on/off various units in order to conserver battery power. For example, a power management unit may be used to shutdown power to a display, WIFI, etc. when the mobile device is used as a music player, e.g., an MP3 player, in order to conserve power. In general each of the powered sub-units in an electronic device is powered by its own power regulator to allow each sub-unit to be controlled independently.
Conventionally, two methods are used in power management units. The first method uses linear regulators. The second method uses switching regulators.
Linear regulators are in general small and use few external components. Unfortunately, linear regulators become very inefficient when the difference between their input and output voltage increases because linear regulators regulate the input and output voltage by internally dissipating power. For example, more power is dissipated when the difference between the input voltage and the output voltage is 2 volts in comparison to when the difference between the input voltage and the output voltage is 0.5 volt. As a result, the greater the difference between the input and output voltage, the greater the power dissipation becomes, thus the greater the inefficiency becomes.
In contrast, switching regulators are more efficient than linear regulators because they do not internally dissipate power like linear regulators. Switching regulators regulate the input and output power by storing energy electro-magnetically and releasing it as output voltage on demand. Unfortunately, switching regulators are in general larger, more complex and more expensive to implement in comparison to linear regulators. Moreover, switching regulators use more external components in comparison to linear regulators.